The present invention relates generally to chewing gum and methods of manufacturing same.
During storage, chewing gum has a tendency to lose or gain moisture from the surrounding atmosphere depending on the surrounding temperature, relative humidity, and packaging, and also depending on the shape and formulation of the chewing gum. Sugar-containing chewing gums, for instance, typically contain corn syrup and a small amount of humectant such as aqueous sorbitol or glycerin. Such sugar-containing chewing gums have a tendency to dry out and become brittle when stored under relatively dry conditions of 50% relative humidity and lower. The tendency of sugar gums to dry out and become brittle is particularly apparent at higher ambient temperatures.
Sugarless chewing gums are typically designed to contain lower amounts of moisture than sugar-containing gums. In sugarless gums which are sweetened with aspartame or other moisture-susceptible artificial sweeteners, it is important to maintain a low moisture content in order to prevent loss of sweetness and flavor qualities. However, due to their low initial moisture content and high level of hygroscopic ingredients, these sugarless gums tend to gain moisture at above 40% relative humidity, causing wetness of the chewing gum and degradation of the aspartame or other moisture-susceptible artificial ingredients.
Various technologies have been developed for the purpose of protecting chewing gum from moisture loss, moisture gain and other adverse changes which result from storage. For example, packaging techniques have been developed which provide sealed, high quality protective packaging for individual chewing gum sticks. One such technique is disclosed in U.S. Pat. No. 5,048,260 to Raymond et al.
Other techniques of protecting chewing gum from adverse environmental conditions have involved modifying the chewing gum formulae so as to encapsulate or otherwise protect the individual chewing gum ingredients which are environmentally susceptible. U.S. Pat. No. 4,822,622 to Dokuzovic et al. discloses the use of a protective barrier film through the center of a chewing gum to separate a flavor-containing chewing gum layer from an aspartame-containing chewing gum layer. The barrier film components which are disclosed include gelatin, acacia gum, agar, algin and derivatives, carrageenan and salts thereof, arabinogalactan, baker yeast, glycan, carboxymethylcellulose, carob bean gum, cellulose gum, furcellaran and salts thereof, guar gum, gum arabic, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, Irish moss gelose, karaya gum, locust bean gum, methylcellulose, methylethyl cellulose, pectin, propylene glycol alginate, propylene glycol ether of methylcellulose, sodium carboxy methylcellulose, tragacanth gum, xanthan gum, shellac, and mixtures thereof.
U.S. Pat. No. 4,568,560 discloses a method for encapsulating active ingredients in a coating composition comprising a water soluble film forming composition, an enteric compound and a plasticizer for the film forming composition. U.S. Pat. No. 4,824,680 to Bernatz et al. discloses a method for producing a sugar-based chewing gum having improved wrapability.
Still other techniques of protecting chewing gum from adverse environmental conditions have involved coating the chewing gum with an edible film. Most of these techniques have focussed on the film coating of chewing gum tablets and other confectionery tablets, as opposed to chewing gum sticks. U.S. Pat. No. 4,802,924 and PCT Publication WO 87/07902 disclose the coating of pharmaceutical tablets, foods, confectionery forms and the like with polydextrose, or a combination of polydextrose and cellulosic polymer, or a layer of polydextrose overcoated by a layer of cellulosic polymer. German Patent No. DE 3,043,914 discloses the coating of pharmaceuticals, confectionery products and foods, with an edible film containing methyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, cellulose acetate phthalate, ethyl cellulose, polyvinyl pyrrolidone, sodium ethyl cellulose sulfate, corn protein (zein), and/or poly (vinyl acetate phthalate).
U.S. Pat. No. 4,810,534 to Seaborne et al. discloses a method for preparing a low water permeable, edible film containing cross-linked shellac and one or more edible sources of polyphenolics, benzaldehyde and derivatives, acetylated monoglycerides, polyglycerol esters, straight chain monocarboxylic acid and dicarboxylic acids. U.S. Pat. No. 4,777,046 to Iwakura et al. discloses a sheet-like preparation comprising a drug, a gelatin or agar, gluten, a carboxyvinyl polymer, a polyhydric alcohol, a gum, a wax and a sheet-like support. PCT Publications WO 87/03453 and WO 86/00501 both disclose methods of preparing preformed edible films which include a layer of a hydrophilic polymer selected from the group consisting of edible, film-forming carbohydrates and proteins, and a lipid layer adhered to the hydrophilic layer.
A number of possible "active agents" in gum either are incompatible with other ingredients in gum or react therewith. Sweeteners and flavor are examples of active agents that can adversely interact with other ingredients. Aspartame, for example, is sensitive to at least certain aldehyde flavors, as well as moisture. Due to this characteristic, aspartame cannot be used with certain ingredients or, for example, must be segregated in the gum by a protective barrier layer from other components as discussed above. See U.S. Pat. No. 4,822,622.
In a similar vein, certain ingredients, when used at least in certain gum compositions, do not necessarily exhibit their desired properties. For example, in certain gum formulations, the sweetener thaumatin can become bound up in the gum and therefore is not readily released to produce desired sweetness. Additionally, for certain ingredients, the release rate from the body of the chewing gum may be poor requiring extra ingredients or higher use levels in order to provide sufficient sensory perception.
With respect to active agents in gum, a further issue that arises is with respect to stability during storage. For example, it is known to use flavors in chewing gum. However, at least with respect to certain flavors, the flavors dissipate (evaporate) from the gum. Thus, the chewing gums can lose flavor over time.
In manufacturing gum, another issue is with respect to processing. In order to process chewing gum sticks in an efficient manner, it is desirable that the chewing gum sticks be as rigid as possible. However, this is contrasted with the desire to have soft chewing gum for the user to chew.
In order to improve manufacturing processes, rolling compounds are used. Rolling compounds include sugar, starch, and mannitol. Aside from providing some initial sensory impact, the rolling compound increases the processability of the chewing gum, as well as prevents the chewing gum compositions from binding to the machinery. Additionally, the rolling compound assists in the sheeting and wrapping of the chewing gum.
However, rolling compounds adversely effect chewing gum processing machinery and increase wear. Although it would be desirable to not use a rolling compound, this creates manufacturing problems.